1. Field of the Invention
The present invention relates in general to a weather strip which is mounted to an automotive door window frame, an automotive door opening or the like, and more particularly, the present invention relates to a method and a device for producing such weather strips.
2. Description of the Prior Art
In order to clarify the task of the present invention, a known weather strip used in the above-mentioned automotive field will be described with reference to FIG. 7 of the accompanying drawings.
The known weather strip shown in the drawing is a glass runner 10 which is mounted to the inside wall of an automotive window frame 100.
The glass runner 10 is generally constructed of elastic material, such as natural rubber, synthetic rubber, thermosetting resin or the like.
The glass runner 10 comprises a base portion 1 attached to the window frame 10, side wall portions 3 and 5 raised from both sides of the base portion 1, and lip portions 3a and 5a extending inwardly downward and obliquely from respective tops of the side wall portions 3 and 5 toward the base portion 1. The base portion, the side wall portions 3 and 5 and the lips 3a and 5a constitute a glass runner proper 10'.
Designated by numeral 7 is a window glass which is slidably contactable with the lip portions 3a and 5a during its opening and closing movement.
The inside wall of the base portion 1 and the outside walls of the lip portions 3a and 5a are each equipped with a low friction layer 11 for improving the sliding ability of the window glass 7 relative to the glass runner 10. Due to provision of such friction layers 11, the wear resistance of the glass runner 10 against the window glass 7 is also increased.
The friction layer 11 is usually constructed of thermoplastic resin, such as polyethylene resin (PE), polypropylene resin (PP) or the like.
In order to produce weather strips 10 of the type described hereinabove, many methods have been proposed and put into practical use. Some of them are shown in Japanese Patent First Provisional Publications Nos. 2-269039, 2-269040, 2-269041, 3-24947 and 2-212118. In fact, these publications disclose various methods for providing the glass runner proper 10' with the friction layers 11.
In these conventional methods, the glass runner proper 10' and the friction layer 11 are produced or molded by two different extrusion molding machines, and thereafter the molded two are united through suitable coupling method, such as method of using adhesive, method of partially melting the friction layers 11, method of using a welding device, or the like.
However, such conventional methods have required troublesome working steps due to the usage of two molding machines. This induces increase in production cost of the weather strips. Furthermore, the above-mentioned conventional methods have failed to provide a satisfied joining between the glass runner proper 10' and the friction layers 11.